Services rendered: metabolic serial testing (FSIVGTT, OGTT, mixed-meal), 24-hr energy expenditure by whole-room respiratory chambers, resting energy expenditure, exercise and physical function testing, body composition, objective physical activity monitoring, core/skin temperature, heart rate/blood pressure variability, behavioral, psychological, and neurocognitive assessments, taste tests, sleep measurements[unreadable] [unreadable] In the area of body composition, we successfully validated our new instruments (large-scale dual-energy x-ray absorptiometry - DXA, air-displacement plethysmograph -BodPod, and bioelectrical impedance analyzers - BIA). We have shown excellent reproducibility of the DXA (>99%) and its validity for measuring obese patients using half-scans (manuscript accepted by Journal of Obesity). We also demonstrated the agreement between DXA, Bod Pod, and BIA in a heterogeneous group while showing between-individual differences. We also discovered a small but clinically relevant difference between our new DXA and the DXA scanner used by the Clinical Center Nuclear Medicine Department. This is important not only methodologically, but for comparing studies using different scanners.[unreadable] [unreadable] Similarly, we have successfully modified and validated other measurement techniques for the Metabolic Research Core, such as continuous heart-rate and blood pressure monitors for autonomic nervous system activity assessments, blood-draw isolette systems for the metabolic suites, skin and core body temperature monitors, and multiple portable physical activity monitors. [unreadable] [unreadable] Currently, we are supporting 20+ active protocols for various services, with focuses on producing comprehensive, accurate, and precise measurements of human metabolism. The integration of these measurements will help us understand the complex nature of energy homeostasis in healthy and diseased states.